1. Department of Cardiovascular Medicine, People's Hospital of Wanning, Wanning, Hainan, China;
2. Department of Science and Education, People's Hospital of Wanning, Wanning, Hainan, China; and
3. Department of General Practice, Hainan General Hospital, Hainan Affiliated Hospital of Hainan Medical University, Haikou, Hainan, China.